Figure 5. Step cycle and EMG burst durations at different speeds for one subject.

Subject I. R. was 1.6 months old at the time of testing. A, the step cycle duration decreases with increasing treadmill speed. B, this decrease results entirely from a decrease in the duration of the extensor (GS; •) burst (correlation coefficient, r = 0.89). The flexor (TA; ▾) burst in the swing phase remains unchanged for the different speeds (r = 0.22). Note that the flexor burst at the highest speed in this subject was not sufficiently clear to estimate the duration accurately.